Everyone seems to make a small deal out of reboring and rerifling a barrel, but it is not a normal gunsmithing job. There are very few places that do it and they are all backed up to about three weeks after Doomsday. It will be a lot cheaper to have a new barrel installed, and a lot more practical just to trade the rifle on one in the caliber you want. FWIW, I don't know where you live and/or hunt, but 7mm Magnum will take care of about anything on this continent.